The modem command &Dn (where 'n' is a number) generally sets the modem response to the Data Terminal Ready (DTR) signal from the server's serial port. The desired response is that the modem will hold a connection while DTR is enabled, and drop the connection when DTR is released. This is the mechanism by which the server hangs up on a connection under normal conditions.
Consult your modem manual for its specific response scheme for the &Dn command.
Two strategies are available for dealing with the modem's response to DTR:
vRecovery
vPrevention
Before you use one of these strategies, determine if your server's modem is set up properly to respond to DTR.
With the remote terminal connected to serial port 1 and defined as the Primary Console Device, there are two tests you can perform:
1.Will the modem drop the connection after the System initialization complete message displays at the remote terminal?
If Yes, the modem is set up correctly.
If No, try another &Dn setting for your server's modem. See your modem manual for this information. The &Dn command appears in three places each in three of the sample modem configuration files:
vmodem_f.cfg
vmodem_f0.cfg
vmodem_f1.cfg
.
2.Will the server's modem disconnect when the power drops? You can make this
observation at the remote terminal by commanding your server to shutdown and power off. (The AIX command shutdown
If Yes, this is the correct response. The modem is set up correctly.
If No, try another &Dn setting for your server's modem. See your model manual for this information. The &Dn command appears in three places each in three of the sample modem configuration.
If you are using modem_z.cfg or modem_z0.cfg, you cannot control DTR response. If your remote terminal does not disconnect after logging off, you must command the remote terminal emulator to hang up. This then breaks the connection.
Recovery Strategy
The recovery strategy consists of making two calls to establish a remote session. This is the easiest solution to implement, and allows more freedom for configuring your server's serial ports.
17644P Series Model 170 User's Guide
